1. Field of the Invention
The present invention generally relates to optical scanning devices, imaging apparatuses, and imaging methods, and more particularly to an optical scanning device including a plurality of scanning optical systems having a plurality of light sources and arranged in a main scanning direction, an imaging apparatus forming an image by means of such an optical scanning device, and an imaging method using such an optical scanning device.
2. Description of the Related Art
An optical scanning device scanning a surface to be scanned (a scanned surface) with a light beam from a light source deflected by a deflector and passing through a scanning optical element can cover a large scanning area by dividing the scanned surface in a main scanning direction even if the optical scanning device is compact. Further, since the optical scanning device has each of its scanning optical systems and scanning optical elements reduced in size, it becomes easy to correct wave front aberration correlated greatly with a beam spot diameter so that a variation in the beam spot diameter due to a component variation or a component attachment error can be minimized.
On the other hand, the scanning optical system can have a higher scanning rate by including a plurality of light beams.
However, if the scanned surface is divided in the main scanning direction, a deviation between recording positions at the joint of scanning areas causes image degradation. Further, if each scanning optical system employs a plurality of light beams, it is difficult to match the recording positions in a sub scanning direction.
Japanese Laid-Open Patent Application No. 10-246861 discloses an apparatus that correct the joint of scanning areas in the main scanning direction by controlling the recording timing of one of a pair of laser scanning optical systems.
However, if each of the laser scanning optical systems employs a plurality of light beams, recording positions are prevented from being matched in the sub scanning direction with high accuracy.
It is a general object of the present invention to provide an optical scanning device, an imaging apparatus, and an imaging method in which the above-described disadvantages are eliminated.
A more specific object of the present invention is to provide an optical scanning device, an imaging apparatus, and an imaging method by which a recording end position in the scanning area of a first scanning optical system and a recording start position in the adjacent scanning area of a second scanning optical system can be matched with high accuracy in main and sub scanning directions.
The above objects of the present invention are achieved by an optical scanning device including a plurality of scanning optical systems arranged in a main scanning direction each including a plurality of light sources emitting light beams, a light source driving circuit modulating the emitted light beams separately, and a deflector causing the light beams to perform scanning, wherein at least one of the scanning optical systems comprises a light source selection part selecting one of the light sources of the one of the scanning optical systems.
According to the above-described optical scanning device, one of the light sources of the one of the scanning optical systems which one includes the light source selection part is selected so as to minimize a deviation in the sub scanning direction between scanning start and end positions in the scanning area of the one of the scanning optical systems and a scanning area adjacent thereto at the joint of the two scanning areas. Therefore, the optical scanning device can perform scanning with the scanning start and end positions being matched in the sub scanning direction with high accuracy at the joint of the scanning areas.
Additionally, the light source driving circuit may include a function of correcting a modulation frequency for each of the light beams.
Thereby, the optical scanning device can perform scanning with the scanning start and end positions being matched also in the main scanning direction with high accuracy at the joint of the scanning areas.
The above objects of the present invention are also achieved by an imaging apparatus including an optical scanning device having a plurality of scanning optical systems arranged in a main scanning direction, wherein the scanning optical systems each includes a plurality of light sources emitting light beams, a light source driving circuit modulating the emitted light beams separately, and a deflector causing the light beams to perform scanning, and at least one of the scanning optical systems includes a light source selection part selecting one of the light sources of the one of the scanning optical systems.
The above-described imaging apparatus includes an optical scanning device that produces the same effects as described above. Therefore, the above-described imaging apparatus can improve the quality of an output image.
Additionally, the light source driving circuit of the above-described imaging apparatus may include a function of correcting a modulation frequency for each of the light beams.
Thereby, for the same reason as described above, the above-described imaging apparatus can improve the quality of an output image.
The above objects of the present invention are also achieved by an imaging method employing an optical scanning device including a plurality of scanning optical systems arranged in a main scanning direction, the imaging method including the steps of (a) generating a light source selection signal in at least one of the scanning optical systems to select one of light sources thereof, the one of the light sources being used for recording image information of a first line of a scanning area scanned by the one of the scanning optical systems, (b) emitting light beams from the light sources in the one of the scanning optical systems, the light beams being modulated separately by a light source driving circuit of the one of the scanning optical systems, and (c) performing scanning with the light beams being deflected by a deflector of the one of the scanning optical systems.
According to the above-described imaging method, one of the light sources of the one of the scanning optical systems which one includes the light source selection part is selected so as to minimize a deviation in the sub scanning direction between scanning start and end positions in the scanning area of the one of the scanning optical systems and a scanning area adjacent thereto at the joint of the two scanning areas. Therefore, scanning can be performed with the scanning start and end positions being matched in the sub scanning direction with high accuracy at the joint of the scanning areas.
Additionally, the above-described imaging method may further include the step of (d) correcting a modulation frequency for each of the light beams by the light source driving circuit.
Thereby, scanning can be performed with the scanning start and end positions being matched also in the main scanning direction with high accuracy at the joint of the scanning areas.